Red Hat Enterprise Linux 8 was released in Beta on November 14, 2018. There are so many features and improvements that distinguishes it from its antecedent – RHEL 7. In this blog, I’m attempting to provide a quick glance of those improvements, deprecations and the upgrade path.
- YUM command is not available and DNF command replaces it. If you’ve worked on Fedora, DNF was a the default package manager in it.
- chronyd is the default network time protocol wrapper instead of ntpd
- Repo channels names changed, but content of them is mostly the same. CodeReady Linux Builder repository was added. It is similar to EPEL and supplies additional packages, which are not supported for production use.
- One of the biggest improvement in RHEL 8 system performance is the new upper limit on physical memory capacity. Now has 4 PB of physical memory capacity compared to 64TB of system memory in RHEL 7
- RPM command is also upgraded. The rpmbuild command can now do all build steps from a source package directly. the new –reinstall option allows to reinstall a previously installed package. there is a new rpm2archive utility for converting rpm payload to tar archives.
- TCP networking stack is Improved. RedHat claims that the version 4.18 provides higher performances, better scalability, and more stability
- RHEL 8 supports Open SSL 1.1.1 and TLS 1.3 cryptographic standard by default
- BIND version is upgraded to 9.11 by default and introduces new features and feature changes compared to version 9.10.
- Apache HTTP Server, has been updated from version 2.4.6 to version 2.4.37 between RHEL 7 and RHEL 8. This updated version includes several new features, but maintains backwards compatibility with the RHEL 7 version
- RHEL 8 introduces nginx 1.14, a web and proxy server supporting HTTP and other protocols
- OpenSSH was upgraded to version 7.8p1.
- Vim runs default.vim script, if no ~/.vimrc file is available.
- The ‘nobody’ & ‘nfsnobody’ user and groups are merged into ‘nobody’ ID (65534).
- In RHEL 8, for some daemons like cups, the logs are no longer stored in specific files within the /var/log directory, which was used in RHEL 7. Instead, thet are stored only in systemd-journald.
- Now you are forced to switch to Chronyd. The old NTP implementation is not supported in RHEL8.
- NFS over UDP (NFS3) is no longer supported. The NFS configuration file moved to “/etc/nfs.conf”. when upgrading from RHEL7 the file is moved automatically.
- For desktop users, Wayland is the default display server as a replacement for the X.org server. Yet X.Org is still available. Legacy X11 applications that cannot be ported to Wayland automatically use Xwayland as a proxy between the X11 legacy clients and the Wayland compositor.
- Iptables were replaced by the nftables as a default network filtering framework. This update adds the iptables-translate and ip6tables-translate tools to convert the existing iptables or ip6tables rules into the equivalent ones for nftables.
- GCC toolchain is based on the GCC 8.2
- Python version installed by default is 3.6, which introduced incompatibilities with scripts written for Python 2.x but, Python 2.7 is available in the python2 package.
- Perl 5.26, distributed with RHEL 8. The current directory . has been removed from the @INC module search path for security reasons. PHP 7.2 is also added
- For working with containers, Red hat expects you to use the podman, buildah, skopeo, and runc tools. The podman tool manages pods, container images, and containers on a single node. It is built on the libpod library, which enables management of containers and groups of containers, called pods.
- The basic installation provides a new version of the ifup and ifdown scripts which call NetworkManager through the nmcli tool. The NetworkManager-config-server package is only installed by default if you select either the Server or Server with GUI base environment during the setup. If you selected a different environment, use the yum install NetworkManager-config-server command to install the package.
- DNF modules improve package management.
- New tool called Image Builder enables users to create customized RHEL images. Image Builder is available in AppStream in the lorax-composer package. Among other things, it allows created live ISO disk image and images for Azure, VMWare and AWS, See Composing a customized RHEL system image.
- Some new storage management capabilities were introduced. Stratis is a new local storage manager. It provides managed file systems on top of pools of storage with additional features to the user. Also supports file system snapshots, and LUKSv2 disk encryption with Network-BoundDisk Encryption (NBDE).
- VMs by default are managed via Cockpit. If required virt-manager could also be installed. Cockpit web console is available by default. It provides basic stats of the server much like Nagios and access to logs. Packages for the RHEL 8 web console, also known as Cockpit, are now part of Red Hat Enterprise Linux default repositories, and can therefore be immediately installed on a registered RHEL 8 system. (You should be using this extensively if you’re using KVM implementations of RHEL 8 virtual machines)
- Yum package is deprecated and Yum command is just a symbolic link to dnf.
- NTP implementation is not supported in RHEL8
- Network scripts are deprecated; ifup and ifdown map to nm-cli
- Digital Signature Algorithm (DSA) is considered deprecated.. Authentication mechanisms that depend on DSA keys do not work in the default configuration.
- rdist is removed as well as rsh and all r-utilities.
- X.Org display server was replaced by Wayland’ from Gnome
- tcp_wrappers were removed. Not clear what happened with programs previously compiled with tcp-wrapper support such as Postfix.
- Iptables are deprecated.
- Limited support for python 2.6.
- KDE support has been deprecated.
- The Up-gradation from KDE on RHEL 7 to GNOME on RHEL 8 is unsupported.
- Removal of Btrfs support.
- Docker is not included in RHEL 8.0.
Release of RHEL 8 gives opportunity for those who still are using RHEL 6 to skip RHEL 7 completely for new server installations. RHEL 7 has five years before EOL (June 30, 2024) while many severs last more then five years now. Theoretically upgrade from RHEL 6 to RHEL 8 is possible via upgrade to RHEL 7 first, but is too risky. RHEL 8 is distributed through two main repositories: Please follow RHEL8 Upgrade path.
Content in the BaseOS repository is intended to provide the core set of the underlying OS functionality that provides the foundation for all installations. This content is available in the RPM format and is subject to support terms similar to those in previous releases of RHEL. For a list of packages distributed through BaseOS.
Content in the Application Stream repository includes additional user space applications, runtime languages, and databases in support of the varied workloads and use cases. Application Streams are available in the familiar RPM format, as an extension to the RPM format called modules, or as Software Collections. For a list of packages available in AppStream,
In addition, the CodeReady Linux Builder repository is available with all RHEL subscriptions. It provides additional packages for use by developers. Packages included in the CodeReady Linux Builder repository are unsupported. Please check RHEL 8 Package manifest.
With the idea of the Application stream, RHEL 8 is following the Fedora Modularity lead. Fedora 28, released earlier this year, by Fedora Linux distribution (considered as bleeding edge community edition of RHEL) introduced the concept of modularity. Without waiting for the next version of the operating system, Userspace components will update in less time than core operating system packages. Installations of many versions of the same packages (such as an interpreted language or a database) are also available by the use of an application stream.
Theoretically RHEL 8 will be able to withstand more heavy loads due to optimized TCP/IP stack and improvements in memory handling.
Installation has not been changed much from RHEL 7. RHEL 8 still pushes LVM for root filesystem in default installation. Without subscription you can still install packages from ISO, either directly or making it a repo. The default filesystem remains XFS, RedHat EnterpriseLinux 8 supports installing from a repository on a local hard drive. you only need to specify the directory instead of the ISO image.
Kickstart also has changed but not much ( auth or authconfig are depreciated & you need to use authselect instead)
Source: Red Hat RHEL8 release notes, Red Hat Blogs, Linux Journal etc